Isolation, characterization and response surface method optimization of cellulose from hybridized agricultural wastes

This study explores the utilization of eight readily available agricultural waste varieties in Nigeria—sugarcane bagasse, corn husk, corn cob, wheat husk, melina, acacia, mahogany, and ironwood sawdust—as potential sources of cellulose. Gravimetric analysis was employed to assess the cellulose content of these wastes, following which two selected wastes were combined based on their cellulose content and abundance to serve as the raw material for the extraction process. Response Surface Methodology, including Box-Behnken design, was applied to enhance control over variables, establish an optimal starting point, and determine the most favorable reaction conditions. The cellulose extracted under various conditions was comprehensively examined for content, structure, extent of crystallinity, and morphological properties. Characterization techniques such as X-ray Diffraction, Scanning Electron Microscopy, and Fourier Transform Infrared Spectroscopy were employed for detailed analysis. Compositional analysis revealed sugarcane bagasse and corn cob to possess the highest cellulose content, at 41 ± 0.41% and 40 ± 0.32% respectively, with FTIR analysis confirming relatively low C=C bond intensity in these samples. RSM optimization indicated a potential 46% isolated yield from a hybrid composition of sugarcane bagasse and corn cob at NaOH concentration of 2%, temperature of 45 °C, and 10 ml of 38% H2O2. However, FTIR analyses revealed the persistence of non-cellulosic materials in this sample. Further analysis demonstrated that cellulose isolated at NaOH concentration of 10%, temperature of 70 °C, and 20 ml of 38% H2O2 was of high purity, with a yield of 42%. Numerical optimization within this extraction condition range predicted a yield of 45.6% at NaOH concentration of 5%, temperature of 45 °C, and 20 ml of 38% H2O2. Model validation confirmed an actual yield of 43.9% at this condition, aligning closely with the predicted value. These findings underscore the significant potential of combinning and utilizing agricultural wastes as a valuable source of cellulose, paving the way for sustainable and resource-efficient practices in various industrial applications.


Isolation of cellulose
Cellulose was isolated from combined sugarcane bagasse and corn cob through sequential chemical treatment (Alkali treatment and hydrogen peroxide bleaching) described by Enriquez et al. and Fitriana et al. 25,35 with slight modification.Instead of using glacial acetic acid to neutralize the mixture following the alkalization process, 0.2 M citric acid was employed in this instance.Corn cob and sugarcane bagasse were mixed with NaOH, diluted with distilled water, and filtered through Whatman No.4 filter paper.The resulting fibrous matter was then transferred to a clean beaker for bleaching, where 38% H 2 O 2 was added, and the pH adjusted with 2 M citric acid.The mixture was then cooled, filtered, and dried before storage in a Ziploc container for future use. Figure 2 summarizes the cellulose extraction procedure.The % extraction yield of cellulose was calculated for each sample using Eq.(1).

Experimental design for cellulose extraction
RSM which includes the BBD, was used with design expert software (version 13.0.5.0) to design the experiment to isolate cellulose from the combined sugarcane bagasse and corn cob waste.The NaOH concentration (A), extraction temperature (B), and volume of H 2 O 2 (C), were the independent factors while the (dependent variable) response was % cellulose yield.The polynomial equation (Eq.2) was employed to characterize the effects of variables, incorporating linear, quadratic, and cross-product terms.
where, Y refers to yield of cellulose, β is the regression coefficients, k is the number of factors studied in the experiment and ε is and the residual error, respectively.The experimental factors were coded according to Eq. ( 3) for the development of the regression equation.
where i = 1,2, . . ., k .X is the dimensionless value of an independent variable,X i is the real value of an independent variable, X 0 is the real value of the independent variable at the center point, and X i is the step change value 36 .Table 1 presents the RSM design along with coded levels.These factors selected based one-factor-a-time preliminary optimization assessment.The estimation of the requisite number of experimental runs to develop the model is formulated as N = 2k(k − 1) + C 0 , where k denotes the number of factors, and C 0 represents the count of central points 37 .This generated 17 experimental runs.To mitigate the influence of unforeseen variability in the observed responses, the experimental runs were randomized 38 .The significant terms (p-value < 0.05) of the model were determined through analysis of variance (ANOVA).The effectiveness of the model in predicting response values was assessed.The optimized conditions were confirmed through experimental validation under the optimized settings.

FTIR analysis
The Agilent Cary 600 series FT-IR spectrometer was used to evaluate the characteristics of the functional groups of the produced cellulose samples as well as the untreated sample.The FTIR spectra were recorded in a transmittance range of 4000 cm −1 to 650 cm −1 .

SEM analysis
A Phenom ProX desktop scanning electron microscope with energy dispersive X-ray capability (SEM-EDX) was used to study the microstructure of both the synthesized cellulose and untreated samples.The samples were scanned at 15 kV at magnification of 1000×.Prior to analysis, the sample's surface had a tiny, conductive layer of gold applied to it.

XRD analysis
The Rigaku miniflex x-ray diffractometer manufactured by Japanese X-ray scientific, analytical, and industrial instrumentation cooperation was used.The degree of crystallinity of the raw material and isolated cellulose was studied using an XRD diffractometer.The device was operated with Cu K alpha radiation at a wavelength of 1.54 angstroms at 40 kV and 15 mA.Crystallinity index (C.I) calculation used a Segal et al. 39 proposed formulation.In this approach, the x-ray total crystallinity (%) of cellulose is calculated from the peak height ratio between the intensity of the crystalline peak (I crystalline ) and total intensity after subtraction of background signal (I amorphous + I crystalline ) as shown in Eq. ( 4) 37 .

Compositional analysis and FTIR characterization of the selected agricultural wastes
The chemical compositions of the eight agricultural wastes are summarized in Table 2.The experiment was conducted in duplicates.Cellulose was shown to be the predominant component in all biomass samples, surpassing both hemicellulose and lignin contents.These findings are consistent with established literature 27,34,[40][41][42][43] .According to the results, sugarcane bagasse offered the largest percentage of cellulose (41 ± 0.41%) and the lowest amount of hemicellulose, making it an excellent choice for cellulose isolation.Corn cobs also had low lignin levels and a significant amount of cellulose (40 ± 0.32%).In addition to their respective cellulose contents, sugarcane and corn cob are readily available and require little preparation.Therefore, they were selected to form the raw materials for isolation.The average lignocellulose composition of whole corn cob reported by several researchers is in the range of 33 to 43% cellulose, 26 to 36% hemicellulose, and 17 to 21% lignin.Similarly, sugarcane bagasse contains 38 to 50% cellulose, 15 to 28% hemicellulose and 13 to 24% lignin 44 .The quantity of these components has a considerable impact on their accessibility and suitability for bioproducts and biopolymer synthesis.Given its abundant and cost-effective availability, agricultural waste in general stands as a promising source of cellulose, driving forward green economic growth.Figure 3 shows the FTIR spectra while the polymers, allocated bands, and functional groups were identified in Table 5. Owing to the intricate nature of the eight biomass samples, their spectra displayed several peaks along with a range of functional groups, including aromatics, alkenes, and carbonyls.The strong correlation between the spectra and peaks indicates that the biomass material has similar functional groups.The O-H group of the intermolecular and intramolecular hydrogen bonds in the cellulose molecules exhibits free O-H stretching vibrations, which are the dominant broad band present in all spectra at about 3300 cm −1 .The organic components of polysaccharides are typically linked to the C-H stretching vibration observed in the spectra between 2800 and 2900 cm −1 .Similar findings on various plant biomass for cellulose extraction were reported in previous works 5,41,45,46 .The C=C aromatic skeletal vibration of hemicellulose and lignin in the structure has been linked to the FTIR spectra of the two materials, which are represented by peaks in the wavenumber at approximately 1500 and 1700 cm −1 , respectively.An absorption band at around 1200 cm −1 is linked to the ether linkage's C-O stretching.The C-O-C of the pyranose skeletal ring is connected to the strong absorption peaks near the 1050 cm −1 linked explicitly to cellulose 27,33,41,47 .The results obtained from this investigation align with the conclusions documented in previous studies.Hence, these bands resemble those found in the FTIR spectra of lignin, hemicellulose, and cellulose.In comparison, the intensity of the OH peak in sugarcane bagasse is notably higher, while the intensity of the C=C stretching peak is lower.This suggests a relatively higher presence of cellulose and hemicellulose, aligning with the findings of the compositional analysis detailed in Table 2.

Cellulose isolation and optimization
To efficiently isolate cellulose, biomass must undergo thorough pre-treatment to remove non-cellulosic components, thereby enriching the cellulose content and enhancing its accessibility during subsequent processing stages, while also facilitating the solubilization of lignin and hemicellulose 28,35,48,49 .Figure 4 illustrates some of the extracted cellulose samples, including those treated with alkali and those devoid of extractives.Notably, alkalization prior to bleaching had minimal impact on the colour of the isolated cellulose, with a transition to (4) Table 2.Chemical composition of the different agricultural wastes.an off-white hue observed post-bleaching.This finding resonates with observations made by Enriquez et al. 35 during the cellulose extraction process from spring-harvested switchgrass.Table 3 summarizes the percentage yield of cellulose obtained under various reaction conditions.Appreciative yield was achieved at 2% NaOH and 45 °C with 10 mL H 2 O 2 , while a low yield resulted from treatment with 18% NaOH at 95 °C with 20 mL H 2 O 2 .This discrepancy may stem from incomplete dissolution of lignin and hemicellulose by 2% NaOH at 45 °C, leaving behind non-cellulosic cellulose, or from overly harsh reaction conditions causing cellulose degradation, as evidenced by the lowest yield from treatment with 18% NaOH at 95 °C.While executing the procedure under ideal reaction conditions at its lowest possible level produced a higher percent yield, the resulting purity was not at its best.This further shows that, even if working under such ideal conditions could seem profitable, the isolated cellulose may still contain a desired proportion of non-cellulosic components when it comes to cellulose isolation from lignocellulosic.So, it is highly recommended to further define isolated cellulose to achieve the optimal reaction conditions and create a decent and pure product.Seven of the seventeen samples labelled A to G (Table 3) were chosen for characterization since they were analyzed under various reaction circumstances (high NaOH concentration/temperature as well as low NaOH concentration/temperature).This will help determine whether the alkalization reaction is greatly affected by temperature and what concentration is best for isolating the cellulose.www.nature.com/scientificreports/It's worth mentioning that alkaline treatment disrupts the intricate matrix among cellulose, hemicellulose, and lignin present in lignocellulosic materials, facilitating cellulose isolation 28 .Exposed components are subsequently solubilized and washed away (Fig. 5), with alkali treatment effectively removing hemicellulose, waxes, oils, and a portion of lignin.The efficiency of impurity removal is influenced by temperature, duration, and alkali concentration.During treatment, cellulose undergoes division, rearrangement, and compaction to alleviate internal strain, resulting in increased hydroxyl group availability for chemical reactions with fibers and polymers.Moreover, alkali solutions disrupt hydrogen bonds and alter fiber arrangement, enlarging fibers and reducing crystallinity.Subsequent neutralization and drying processes modify porosity and elevate crystallinity, ultimately renewing cellulose fibers 35,50 .
The peroxide bleaching procedure, conducted under alkaline conditions, yields effects akin to alkali treatment while efficiently whitening natural fibers.In alkaline environments, H 2 O 2 dissociates into hydrogen ions (H + ) and perhydroxyl ions (OOH .).The perhydroxyl ion, a strong nucleophile, is the chemical species responsible for the bleaching effect on natural fibers.The release of H + explains its behaviour as a weak acid, while the − OOH interacts with another hydrogen peroxide molecule, forming free radicals.These ions ( .OH and .OOH) continue to react with unreacted hydrogen peroxide, decomposing it and generating perhydroxyl radicals until all hydrogen peroxide molecules are consumed, resulting in water and oxygen as the final products 50,51 .However, in the presence of pigments, electrons are abstracted from the chromogens, leading to their breakdown in a redox reaction, thereby reducing their optical absorption 50 .When used in conjunction with alkali treatment, the bleaching process can solubilize and remove remaining non-cellulosic components, particularly lignin, which may not have been effectively removed previously, while simultaneously providing a whitening effect 26 .Conspicuously, the effectiveness of hydrogen peroxide bleaching increases with its pH, which is why bleaching fibers after the alkali treatment is always preferable 25 .
Table 4 presents the analysis of variance (ANOVA) results of the quadratic model for cellulose isolation.The coefficient of determination (R 2 ) for the quadratic model was 0.9843.In a normal way, a R 2 value higher than 0.9 illustrates a high correlation which suggest that 98.43% of the total variance can be explained by the model 48 .Similar finding was reported when cellulose was extracted from jute fiber and the extraction process Table 3. Factors and response for process optimization.www.nature.com/scientificreports/ was optimized using BBD 35 .The adjusted R 2 was reported to be 0.9582 which is high enough to confirm the significance of the model.The f-value of 37.69 and the extremely low probability value of 0.0001 indicate the significance of the model as well.With a lack of fit value of 0.3152 (not significant), the model was found to be sufficient to both predict the response and explain how variables affected it.Table 3 appropriate precision is demonstrated by the signal-to-noise ratio of 21.3639, which further suggests an adequate signal.As a result, this model can be utilized to explore the design space.Overall, the ANOVA findings confirm that the model is suitable and reliable for isolating cellulose.Figure 6 shows the plot of the response predicted from the empirical model and actual values obtained from the experiment.Most of the data points on this plot lie close to the experimental values due to closeness of the actual and predicted yields indicating good performance.

Selected samples for characterization
Most of the data points on this plot lie close to the experimental values due to closeness of the actual and predicted yields indicating good performance.The maximum experimental yield achieved was 46% and it occurred when the variable factors were set to 2% NaOH, 45 °C and 10 mL. Figure 8 displays a 3-D response plot created from response surface approach that examines the impact of synthesis parameters on the cellulose isolation yield.Each 3-D plot represented combinations of the two test variables while the other variables were maintained at the center level.The relationship between the yield percentage from cellulose isolation and temperature (B), NaOH concentration (A), and their reciprocal interactions is depicted in Fig. 7a.Reduced    www.nature.com/scientificreports/temperature and extraction time for the cellulose isolated resulted in an increase in the yield that is achieved.This is because not enough NaOH was present to eliminate most of the hemicellulose and some fraction of the lignin.In Fig. 7b, the yield of isolated cellulose is used to illustrate the impacts of NaOH concentration (A), H 2 O 2 volume (B), and their mutual interaction which collectively could be observed.Yet, the yield of cellulose increased with the reduction of NaOH, and the yield of cellulose increased with increasing volume of H 2 O 2 .The influence of temperature (B), H 2 O 2 volume (C), and their reciprocal interactions with respect to the isolated cellulose yield are also displayed in Fig. 7c.It is noteworthy that these two factors did not interact excessively.However, the highest yield was noted at the lowest temperature and the highest possible H 2 O 2 volume.Overall, the exhibited 3-D graph demonstrated the degree of interaction between the independent factors and the % cellulose yield.

Structural analyses of isolated celluloses
FTIR analysis was conducted on selected cellulose yields (A-G) from Table 3, encompassing a spectrum of extraction conditions, to assess their composition in comparison to the extract-free sample H.The results are depicted in Fig. 8.The observed FTIR spectra exhibit significant similarity, indicating comparable chemical compositions as corroborated by compositional analysis results.The broad absorption bands evident in all spectra around 3300 cm −1 are attributed to the stretching vibration of inter-molecular and intra-molecular O-H groups, indicative of the presence of aliphatic moieties in polysaccharides 47 .Similarly, the C-H vibrations observed in the region of 2900 cm −1 across all spectra are associated with the general organic constituents of the major components, namely the alkyl group present in all three major components.Notably, a peak evident in the region of 1700 cm −1 , related to the C=O stretching vibration found specifically in lignin, was observed solely in the spectrum of the raw sample (sample H), and was absent in the spectra of the isolated cellulose.This observation suggests the successful removal of these components following the alkali and bleaching processes.Additionally, peaks observed around 1500 cm −1 and 1300 cm −1 correspond to the C=C stretching vibration of lignin and C-O stretching vibrations of hemicellulose, respectively.Furthermore, significant peaks observed at 1080 cm −1 and 890 cm −1 are associated with C-O-C and C-O stretching at the β-glycosidic links, consistent with the presence of cellulose in all samples.Importantly, the absence of the C=C bending vibration at approximately 830 cm −1 , initially present in the spectrum of the untreated sample, suggests the successful elimination of lignin from the isolated cellulose following the twostep chemical treatment performed on all samples 47 .Among the samples, Sample F (2% NaOH, 45 °C, 10 mL H 2 O 2 ) yielded the highest cellulose content based on compositional analysis (Table 3).However, the FTIR spectra revealed small peaks around 1500 cm −1 and 1200 cm −1 , indicative of residual C=C stretching and C-O ring vibrations, respectively, suggesting incomplete removal of lignin.This indicates that the isolation of cellulose under mild reaction conditions may not be sufficient to completely solubilize all non-cellulosic components, resulting in impure cellulose.Conversely, Sample G (18% NaOH, 95 °C, 20 mL H 2 O 2 ) exhibited the absence of peaks associated with hemicellulose and lignin, indicating successful elimination of these fractions despite yielding lower cellulose content.However, the severity of the reaction conditions may have led to cellulose degradation, resulting in decreased cellulose recovery.For the remaining samples, A, B, C, D, and E, their individual spectra demonstrate satisfactory removal of hemicellulose and lignin, as no peaks associated with these components were observed (Table 5).

SEM analysis
The SEM analysis in Fig. 9 reveals the surface morphology of the extract-free and the isolated cellulose samples across various stages.In its untreated state (Fig. 9H), the sample exhibited a smooth, pristine surface with scant pores, reflecting its composition comprising hemicellulose, pectin, wax, and other impurities, all bound together by lignin 35 .Following alkaline treatment and hydrogen peroxide bleaching, all samples exhibited a rough and flaky surface, likely attributed to defibrillation and the removal of non-cellulosic components 26 .Because lignin in the hybridized sample could be oxidized and solubilized using peroxide bleaching, more voids and cellulose fibrils were visible in the structure of the isolated cellulose.Additionally, the combined chemical treatment of all the samples had a stronger peeling effect on the larger-pored fibers, which naturally increased surface area and improved cohesion of the fibers inside the matrix, enhancing physical interlocking to improve bonding and strength 29,35 .Similar observation was reported for extracted cellulose from different lignocellulosic 25,26,35,52 .
Small holes, less surface roughness and flakiness were observed in Sample F (Fig. 9F) indicating that not all the complex matrix was disrupted.This supported the FTIR result which shows that not all hemicellulose and/ www.nature.com/scientificreports/or lignin were eliminated in the sample.This is because cellulosic biomass structure is protected, stiffened, and impermeable by the lignin, hemicellulose, and waxes and therefore requires optimum isolation condition for the component of interest 53 .Satisfactory flakiness and roughness of the fiber surface was observed for all the remaining samples when the NaOH concentration was increased (Fig. 7a-e).Moreover, the process temperature affects the level of surface roughness, as shown in Fig. 9.While the cellulose in both samples were isolated under 2% NaOH in a comparable way, sample A showed a rougher surface and flakiness when the temperature was elevated from 45 to 95 °C than sample F. This finding suggests that the temperature during the alkali treatment is also important.These conclusions will be validated further by the XRD analysis results.

XRD analysis
Figure 10 displays the untreated and isolated cellulose's diffraction pattern.Table 6 gives each sample's estimated % C.I and peak height.This technique was adapted to verify whether the non-cellulosic components were successfully confiscated.For the untreated sample as well as the cellulose samples, the primary diffraction peaks are seen at 2θ = 16°, 22° and 34°, which correspond to the crystallographic planes of (1-10), ( 110), ( 200) and (040) indicating the cellulose I structure 17,27,48 .The result showed that both the cellulose samples and untreated sample exhibited a crystalline structure denoted by crystalline I. Sample H, the untreated sample has a peak height of 440 cps, corresponding to C.I of 40.7% which is the lowest.The C.I is anticipated to be smaller in the untreated sample than in any of the samples that had undergone the multi-chemical treatment because, some of the non-cellulosic components have solubilized.This is because hemicellulose and lignin are present in the raw sample and both fractions are amorphous in nature 39 .Sample F, which was isolated cellulose at mild conditions (2% NaOH, 45 °C, 10 mL), showed a greater peak intensity of 694 cps correlating to C.I 54.28% than the untreated sample, but it was comparatively lower than the other produced cellulose derived from different reaction conditions.This is www.nature.com/scientificreports/because not all the hemicellulose and lignin have solubilized since alkaline concentration and temperature have a significant impact on the isolation process.It is out of the ordinary that alkaline-peroxide treatment increases the number of overall crystalline areas in produced fiber 48 .This is consistent with the findings from the FTIR and SEM examinations of the synthetic cellulose produced under the same reaction condition, which explains why impurities were found in the recovered cellulose treated in mild medium.
In contrast, Sample G, which was identified as cellulose isolated at 95 °C and 18% NaOH produced the highest peak intensity of 1433 cps giving rise to the highest C.I of 64.13%.It occurred because of the extraction method's ability to destroy and solubilize the sample's hemicellulose and lignin while successfully isolating the cellulose.As a result, the fiber's overall crystallinity significantly increased because lignin and hemicellulose are amorphous components.The above-mentioned result was in line with the higher C.I attained in the extracted cellulose samples from various agricultural wastes 26,29,35,53 .When it comes to how temperature affects the cellulose isolation process as highlighted, sample A's cellulose was found to have a higher C.I of 56.78% than cellulose separated at a lower temperature (sample F), even though both samples used the same concentration of alkali (2% NaOH).Similarly, sample D has a reasonably lower C.I of 57.35% than sample G despite both celluloses were isolated using the same concentration of NaOH (18%).It is reasonable to argue that the temperature at which cellulose is isolated has just as much significance as the alkali concentration utilized.
Even though a high concentration of NaOH frequently causes crystallite order rearrangement to change the cellulose structure from I to II 35 , the combination treatment left the (1-10) plane without any observable peak.This implies that the crystalline structure of the cellulose was not altered by the reaction conditions, which were not harsh enough.Nevertheless, the difference in the mechanical and physical properties of cellulose can be attributed to the hydrogen bonds in its crystalline sections, which are stronger and more numerous than in its amorphous or non-crystalline portions.For example, crystalline domains have more density and flexibility than non-crystalline ones.Additionally, the disordered portions of the polymer material exhibit flexibility and plasticity, while the ordered regions contribute to the material's stiffness and elasticity.The methods utilized for cellulose extraction affect the degree of crystallinity in cellulose microfibrils.

Verification of RSM model
Based on the FTIR, XRD and SEM results, sample C demonstrated the high yield of pure cellulose at the lowest possible temperature and moderate concentration of NaOH.Consequently, numerical optimization was conducted using the desirability function within Design Expert Software.The optimization goals were set within the range of extraction conditions observed for sample C, as detailed in Table 7.A total of fifteen distinct solutions were identified, each comprising varying levels of independent variables.The solution yielding the highest desirability rating (0.95) was selected as the optimized condition (Table 7).Subsequently, an experiment was carried out under this optimized condition to validate the model.The results, presented in Table 7, exhibit a reasonable agreement with the predicted values.

Conclusion
The study successfully isolated cellulose from a blend of sugarcane bagasse and corn cob using a multi-step alkaline extraction and hydrogen peroxide bleaching process.Analysis of eight selected agricultural wastes revealed significant cellulose content, ranging from 33 to 41%.FTIR spectroscopic analysis demonstrated similarities in lignocellulosic materials, indicating common functional groups among cellulose, hemicellulose, and lignin.However, sugarcane bagasse and corn cob showed the highest level of cellulose content and thus chosen for isolation.FTIR analysis also revealed that mild reaction conditions resulted in ineffective cellulose isolation due to residual non-cellulosic fractions, while overly harsh conditions led to cellulose decomposition and reduced recovery.The successful elimination of non-cellulosic components was confirmed by FTIR data, while SEM micrographs highlighted the significant impact of alkali treatment temperature on cellulose morphology.XRD results confirmed the phase composition of cellulose.Optimal isolation conditions, considering cellulose yield, extent of crystallinity, surface characteristics, and absence of non-cellulosic components, were determined as 10% NaOH,70 °C, and 20 mL of H 2 O 2 .This research offers a promising method for cellulose isolation from hybridized agricultural waste, facilitating the production of diverse cellulose-derived bioproducts for various industrial applications.

( 1 )Figure 1 .
Figure 1.Flowchart of the chemical composition analysis of selected agricultural wastes.

Figure 2 .
Figure 2. Flow chart of the synthesis of cellulose from a mixture of sugarcane bagasse and corn cob.

Figure 3 .
Figure 3. FTIR spectra of the eight agricultural wastes selected for compositional analysis.

Figure 5 .
Figure 5. Schematic diagram of the two step alkaline treatment and hydrogen peroxide bleaching.

Figure 6 .
Figure 6.Plot of predicted vs actual of isolated cellulose yield.

Table 4 .
ANOVA for quadratic model cellulose isolation.

Table 5 .
FTIR bands, functional groups and assigned polymer.C cellulose, H hemicellulose, L lignin.

Table 6 .
Peak height at corresponding 2 position.

Table 7 .
Numerical optimization constraints, optimized conditions, predicted and actual yield at optimized condition.